The invention relates to a single-use device for injection, comprising a pre-filled syringe which is provided with a front nose, and supports an injection needle which is protected by a protective cap, and a syringe body which accommodates the said syringe, and is provided with means for locking of the latter in rotation and in translation.
At present, for safety reasons, some injection devices of the above-described type comprise a protective joining piece for the cap, which also serves the purpose of facilitating removal of the protective cap.
These protective joining pieces, which are generally designed to be fitted on the front end of the syringe body, additionally comprise a central sleeve, which is designed to cover the protective cap, and is provided with grasping claws which are clipped onto the rear of the said cap.
Although in practice, protective joining pieces of this type make it possible to fulfil the required objectives, they have a major disadvantage, which consists of the fact that the central sleeve is fitted onto the protective cap by being forced, and, when this fitting takes place, it tends to push this cap rearwards during passage of the sealing neck with which the front nose of conventional syringes is conventionally provided.
The fact of thrusting the cap rearwards in this manner can have two detrimental consequences. In fact, firstly, it can cause damage to the end of the needle, which conventionally is stuck into the cap. In addition, it can give rise to breakage of the seal between the protective cap and the nose of the syringe, at the sealing neck of the latter.
The object of the present invention is to eliminate these disadvantages, and its main objective is to provide a device for injection which is provided with a safety system for protection of the protective cap, which permits easy removal of the latter, and is not likely to damage the needle or detract from the sealing.
For this purpose, the invention relates to a device for injection as described in the foregoing preamble, characterised in that:
it comprises a joining piece, known as a joining piece with claws, which consists of a front wall, and at least two tabs which can be extended radially, and extend longitudinally relative to the front wall, which can cover the protective cap, and are provided with at least one inner claw for grasping the said cap;
the syringe body has an open rear front surface which can permit introduction of the syringe, and an opposite front section, which can be separated, and is delimited by a breakable area, which is disposed such as to be positioned substantially at the front nose of the syringe which is accommodated in the said syringe body, the said section which can be separated comprising a neck which is designed to clamp the tabs of the joining piece with claws, such that the latter ensure that the protective cap is grasped;
the said section which can be separated and the joining piece with claws being provided with conjugated means for locking in translation and in rotation of the latter relative to one another.
According to the invention, and firstly, the joining piece with claws is simply positioned on the protective cap, before the syringe is introduced into the syringe body, and is actually clamped onto the said cap by radial deformation of the tabs at the neck, with which the section which can be separated is provided.
This solution, which consists of trapping the protective cap by means of radial deformation of the tabs of the joining piece with claws, leads to elimination of the risks of damaging the needle and breaking the seal.
However, in order to guarantee this absence of risks, and preferably, each grasping claw of the joining piece with claws is positioned such as to ensure that the protective cap is grasped substantially downstream from the sealing neck.
In addition, according to the invention, the section which can be separated constitutes a protective element which has undeniable advantages in terms of safety, and of inviolability of the protection. In addition, as a result of the locking in rotation and in translation relative to one another of this section which can be separated and of the joining piece with claws, breakage of the breakable area makes it possible to remove simultaneously the said section which can be separated and the joining piece with claws, together with the protective cap which is trapped in the latter, thus providing release directly of the injection needle.
It should also be noted that since the breakage of the breakable area is obtained conventionally by imparting movement of rotation to the section which can be separated, the protective cap is also rotated during this breakage, and its detachment is thus greatly facilitated.
According to an advantageous embodiment, the means for relative locking in rotation and translation of the joining piece with claws and of the section which can be separated comprise:
a plurality of longitudinal catches, which are provided on at least one of the tabs of the joining piece with claws, such as to be positioned downstream from the neck of the section which can be separated of the syringe body, when the syringe is accommodated in the latter; and
a plurality of longitudinal catches which are provided in the section which can be separated, downstream from the neck of the latter, such that the said neck forms a shoulder for stoppage in translation of the joining piece with claws.
In addition, advantageously, the longitudinal catches which are provided in the section which can be separated, are distributed around the entire periphery of the inner surface of the said section which can be separated, such as to dispense with the need to mark the relative angular positioning of the joining piece with claws and of the section which can be separated.
In addition, in order to facilitate by-passing of the neck, and advantageously, the longitudinal catches of each tab of the joining piece with claws are disposed on a boss, which is provided with an inclined front portion, forming a ramp which is designed to facilitate passage of the neck.
For the same purpose, and advantageously, the neck of the section which can be separated consists of an inner boss, provided with an inclined rear portion which forms an access ramp.
Additionally, in order to ensure that the protective cap is trapped satisfactorily, the neck is advantageously disposed such that it is positioned at the grasping claws of the joining piece with claws.
According to an advantageous embodiment, the joining piece with claws comprises four longitudinal tabs which are distributed regularly relative to the axis of the front wall, two of the said diametrically opposite tabs comprising a boss, and the two others, which are known as the grasping tabs, comprising at least one grasping claw.
In addition, advantageously, the grasping tabs each comprise two lateral grasping claws.